Grid for thermionic tubes



June 19, 1928. I

J. J. JACKMAN GRID FOR THERMIONIC TUBES Fiied April 27, 1925 gwuanto'b Patented June 19, 192$.

UNITE JOSEPH J. JACKMAN. or nAnvERs, MASSACHUSETTS. ASSIGNOR Queue-FOURTH To FRANCIS 1-1. CASKIN, F 'DANVERS, MASSACHUSETTS. q

GRID FOR THEM/Ironic Turns.

Application filed April 27, 1925. Serial ivb. 26,199.

spaced one from the other within the bulb or tube as the same is commonly known. The etficiency of suchan arrangement depends in a large degree upon the structural stability of the several elements and their ability to stand vibration and shock. It is also evident that the .efiect of the so called grid in operating as a valve for the elec tronic stream is dependent upon its position with respect to the filament and to the plate.

As contemplatedya plate and a filament, both of conventional type are separated by a grid capable of operating as a valve with great efficiency. As it is customary to give to the filament the form of an inverted letter V, this invention develops a grid which shall conform to the shape of the filament and produce the maximum result in afl'ecting the electronic stream,

Specifically it is an object of this invention to produce a suitable grid capable of withstanding hard usage and severe vibration. A further object of the invention is to give to the grid a configuration which follows generally that of the contained filament.

It is also a further object of this invention to form the grid from a single piece of sheet metal in such a. way that a rigid structure is obtained complying in great degree with the requirements in all such devices.

It will also be apparent'that this invention simplifies the construction and assemblage of these devices and produces an article economically and capable of eflicient operation over a long time.

Further advantages will be evident from the following description of one preferred form of my invention, in which,

Fig. 1 is a vertical section on the line 11 of Fig. 2,

Fig. 2 is a plan view of the device,

Fig. 3 is a sheet metal blank used and Fig. 4 shows the grid as formed from the blank. 7

By way of example, I have shown a glass stem or support 5, of conventional tubular form the upper portion of which is brought 'posts 7, 7, form supports for the opposite plates 8,8, which provide a vertical recess as shown in Fig. 2. One supporting memr es. if

her 7 projects through t-he stem -5 and is,

continued asthe conductor 9. y I

A central, post. 10 is offset around one plate 8 and projects verticall-yabovethe latter in order to form a support for a..hori-.

zontal: wire 11 the end of which terminates within the recess formed by the plates 8 and ccntrallyof the stem 5. r On oppositesides of the upright 10, the stein'member 6 carries lead wires' .12,.12. These lead wires terminate in diver 'ent ends beneath the level of the plates Sand as indicated clearly in Fig- 1. A heating filament 13 is carried .upward from one-wire .12 around the end of'wir'e 11 and back to the. otherwire 12. The wires 12 are connected with the leads l l of the heating circuit.

Vertically disposed in the upperme'mber 6 and between each-pair of members Tand 12 is an upright. rod 15. l

The details above described are those of the conventionally formed thermionic valves and in the usualtype of such devicesjthei members 15; 15'. extend to the top of the.

plates 8 andform supportsupon which a fine Wire is coiled to be operated as avalve.

or grid by" current oscillations received through a lead 16 connected to one of the posts 15. c I i It will be observed that the filament 13v has the form of an inverted letter V. The grid member 17 is made of, sheet metal from a blank of the trapezoidal form shown in Fig. 3. It will be observed that the side edges of this blank are substantially parallel to the side members of the filament 13. The

metal of the member 17 is of sufficient thickder that all points may be of substantially constant distance from the filament Wire 13.

The operation of a thermionic valve of this typeis already Well known and it will be evident that 'the'grid above described possesses many advantages not found in the I conventional form. In the first place being i filament. The disposition of alternate strips or ribbons 18, 19 on opposite sides of the filament establishes a path for the current oscillations from conductor 16 in such manner as'to surround the filament in a uniform manner and With a very'short air gap.

It will be apparent that this structure contributes to the economy and simplicity of manufacture and produces an article capable of long and efiicient service under most adverse conditions.

While one preferred form of my invention has beenillustrated it will be apparent that'numerous minor changes in detail can be carried out Within the scope of the invention as defined in the appended claims.

What I claim is:

v 1. A grid for thermionic tubes consisting of aflat sheet of metal the medial portion of which is transversely slotted for progressively increasing distances throughout its length and the resultant strips bent outwardly to produce a longitudinal tapering passagewayin the plane of said sheetmetal.

2., A-grid for thermionic tubes consisting of aflat sheet of metal'the medial portion of which is transversely slotted for progressively increasing distances throughout its length and the resultant strips alternatelyv bent'outwardly in opposite directions.-

3. A grid for thermionic tubes consisting of a trapezoid of sheet metal having its medial portion slot-ted parallel to its base for varying distances and the resultant strips bent outwardly to form a tapering longitudinal passageway,

4. In a thermionic tube the combination with an inverted V-shaped heating filament, of a grid formed of sheet metal having parallel integral portions of progressively varying lengths alternately disposed on opposite sides of the plane of the filament and terminating at a uniform distance therefrom.

5. In a thermionic tube the combination With an inverted V-shaped heating filament, of a grid formed of sheet metal having parallel integralportions of progressively varying lengths alternately disposed on opposite sides ofthe plane of the filament and termi nat-ing at auniform distance IEI'OIllthGfilEL- ment and in the plane thereof.

6. In combination, a heating filament and a sheet metal grid having parallel integral. portions alternately disposed on opposite sides of the filament said parallel portions extending in the direction of their length a uniform distance beyond the filament.

JOSEPH J. JACKMAN. 

